​​Yellow pea fiber comes from yellow peas (botanical name: Pisum sativum L.), sometimes called dry, smooth, or field peas. This is a pulse plant, which the Food and Agricultural Organization of the UN defines as pod plants grown for the dried, edible peas and beans inside the pods (vs. eaten as green vegetables). The difference is that the pod is not consumed, just the seeds inside. Chickpeas, dried beans, and lentils are other common examples—what most people think of as legumes. Humans have been eating these plants for thousands of years. Yellow peas are the second most farmed legume crop in the world, and have the added benefit, from a farming standpoint, that they also bring nitrogen back into the soil, making them also useful in crop rotation. 

Both the inside of the pea, called the cotyledon, and the outside of the pea, the hull, are edible and have lots of uses as food additives. The hulls are milled or ground to preserve their nutritional qualities and can be ground to different particle sizes to meet various needs. They can be turned into protein supplements, starches, flours, and fibers, and have lots of uses in various foods. Pea products have been used to replace eggs in sweet baked goods and batters, to add texture to soups and crackers, and to emulsify sauces. In wheat breads, they can increase the protein content and enhance moisture; in snack foods like biscotti or staples like pasta, they lower the glycemic index. 

As foods, these peas are a rich source of protein, being high in the essential amino acids leucine, lysine, phenylalanine, and valine, and the non-essential amino acids arginine, aspartic acid, glutamine, and serine. Like other pulses, when combined with grains like wheat or rice, they can provide a well-balanced protein profile. They also offer various key vitamins (B1, B2, B3, B6) and minerals and trace minerals important to human health, such as potassium, magnesium, calcium, zinc, and folate. Yellow peas have more iron and magnesium than green peas, but all peas are more digestible than soybeans or other pulse plants. When compared with maize starch for example, pea starches and flours more effectively controlled glucose levels than did whole wheat or maize flours. 

Yellow peas are full of phytonutrients (phenolic acids, flavonoids, phytates, lectins, saponins, oxalates, and tannins), most concentrated in the hull, which have antioxidative and anticancer properties, such as anti-inflammatory effects. 

Source: https://bellycrush.com/blogs/news/whats-so-special-about-yellow-pea-fiber